The present invention relates to a flow-control valve. More particularly this invention concerns a pilot-controlled, flow-control valve usable for reducing the pressure between a source of fluid under pressure and a fluid-operated load.
A pilot-controlled pressure-reducing valve has a fluid-flow path whose input end is connected to a source of fluid under pressure and whose output end is connected to a fluid-operated load. A valve member along this path forms a restriction therein which is of variable flow cross section. A pilot valve sensitive normally to the pressure or flow at the output side of the flow-control valve establishes the position of its valve member and, therefore, determines the size of the flow cross section through the valve and the pressure drop created thereby.
Such a valve arrangement is relatively effective and can be made quite sensitive. It has, however, the considerable disadvantage that the considerable pressure drop normally effected at the single valve member can cause rapid wear of the control surfaces that form the pressure-controlling restriction. In particular when used in a hydraulic system wherein the hydraulic fluid is water cavitation becomes a considerable problem. This leads to relatively rapid wearing-out of the valve.